The present invention relates to a sealing system for a shaft against strongly wearing gaseous compressed media.
The sealing systems of the above-mentioned general type are known in the art. Such sealing systems must be provided when subsequent machine elements on rotary shafts must be reliably sealed against highly compressed and strongly wearing media such as for example carrier gas-dust suspensions in dense stream region. It is known to seal from atmosphere, as required from practice, low concentrated dust streams with a concentration of approximately 10-30 kg/m.sup.3 in the event of relatively low system pressure approximately 0.2 MPa. These problems in accordance with the prior art are solved by conventional sealing elements or sealing boxes which are eventually expanded by a lubricant ring with a connected lubricant box. In pump and compressors special sealing systems are known which operate with blocking media. The development of the dense stream technology which is used for example in coal dust gasification is connected with higher requirements made to the sealing. Both the dust concentration and the system pressure in this field can be twenty times higher than the above-mentioned values. Experiments show that transmission of these solutions from the sealing systems with low concentrated dust stream with low system pressure to the dense stream technology with high operational pressure and with simultaneous introduction of blocking media leads to service life only approximately 240 hour. Since each sealing box allows insignificant leakage losses in direction of the pressure drop, small dust particles travel with the leakage stream under the sealing box and leads to incrustation on the sliding surface of the sealing box packing thus blocking the shaft in progressing manner.